Handle large numbers when unmarshalling to an operation

[matthew1001]

Relates to #1568

When unmarshalling contract invoke payloads to a Firefly operation, unmarshal numbers to json.Number instead of float64. This avoids unexpected (and silent) precision loss if a large number is included in the input payload.

I've tested this locally in a FF stack:

1. Submit a curl request to invoke a contract's setter function with a very large number:

curl -X 'POST' \
  'http://127.0.0.1:5000/api/v1/namespaces/default/apis/contract1/invoke/store?confirm=true' \
  -H 'accept: application/json' \
  -H 'Request-Timeout: 2m0s' \
  -H 'Content-Type: application/json' \
  -d '{
  "input": {
    "newMin": 1000000000000000000004
  }
}'
{"id":

2. The DB insert of the FF operation has the correct value:

[2024-09-17T10:51:51.702Z] TRACE SQL-> insert query: INSERT INTO operations (id,namespace,tx_id,optype,opstatus,plugin,created,updated,error,input,output,retry_id) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12) (args: [f1aa8675-5018-446c-959e-06d4a7844e0a default 32c056ae-aa63-4042-8bea-9adfdd8982c3 blockchain_invoke Initialized ethereum 2024-09-17T10:51:51.697166508Z 2024-09-17T10:51:51.697166508Z  {"input":{"newMin":1000000000000000000004},"interface":"1875b0b2-e554-4155-9d4b-4bffcde877ad"

3. The input of the FF response matches the request:

{..."type":"blockchain_invoke","status":"Succeeded","plugin":"ethereum","input":{"input":{"newMin":1000000000000000000004},"interface":"1875b0b2-e554-4155-9d4b-4bffcde877ad","key"...}

4. The event from the blockchain comes back correctly:

[2024-09-17T10:51:53.037Z] TRACE WS ws://evmconnect_0:5008/ws read (mt=1): {"batchNumber":9,"events":[{"address":"0xcca8847223ac774e88686f84167060e501c78d0d","blockHash":"0x1ac1955c279c4f94daffcacba235cdeeb05d34ff6d6d958f83c519c5bd538bdd","blockNumber":"47","data":{"newValue":"1000000000000000000004"},"listenerId":"0191eb17-1651-4eb5-1e0b-0072d0621670"

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.75%. Comparing base (6fe5adf) to head (3396044).
Report is 13 commits behind head on main.

Additional details and impacted files

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##             main    #1581   +/-   ##
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  Coverage   99.75%   99.75%           
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  Files         338      338           
  Lines       24223    24227    +4     
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+ Hits        24164    24168    +4     
  Misses         58       58           
  Partials        1        1           

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[EnriqueL8]

Looks good to me

[EnriqueL8]

Chatted that in the future we could have an ffjson in FireFly Common that handles this and we can use it in all place where we unmarshall/decode some payload